Category Archives: alpine

Habitat restoration at Snowy Adit, Kosciuszko National Park

Habitat restoration at Snowy Adit, Kosciuszko National Park

Key words: revegetation, habitat construction, montane, high altitude,fauna.

Introduction. Island Bend Downstream Spoil Dump, known as ‘Snowy Adit’, is one of approximately 30 former-‘Snowy Scheme’ sites in Kosciuszko National Park (KNP) that have undergone rehabilitation and restoration treatments in the last 10 years. The work is part of a program to remediate environmental risks associated with large volumes of rock dumped following underground blasting of tunnels and the cutting of benches for aqueduct pipelines constructed during the former hydro-electric scheme. At Snowy Adit, up to 950,000m3 of rock spoil was excavated and dumped. The footprint of the site is roughly 11 hectares, about 750m long and 150m wide.

Snowy Adit precinct 2008

Fig 1. Snowy Adit precinct 2008

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Fig 2. Snowy Adit precinct 2015

The site sits at an altitude of 1000m on the northern bank of the Snowy River at the junction with the Gungarlin River. The surrounding landscape is relatively intact, providing a reference ecosystem for the project, and occurs in a transitional zone between montane and sub-alpine vegetation. The dominant overstorey species is Ribbon Gum (Eucalyptus viminalis) with the sporadic occurrence of Candlebark (Eucalyptus rubida). The mid layer is dominated by wattle (Acacia species), and the shrub to ground layer includes Narrow-leaf Bitter Pea (Daviesia mimosoides), Burgan (Kunzea ericoides), Bidgee-widgee (Aceana nove-zelandiae), Carex (Carex appressa) and native grass (Poa helmsii). Within the rehabilitation site prior to works, the dominant species were weeds, aside from several shrubs of Burgan and the occasional Ribbon Gum.

Rehabilitation at Snowy Adit aims to restore a level of ecological function and stability by reducing erosion and re-establishing native vegetation. This gives long term protection to adjoining waterways and reduces the risk of weed invasion and habitat loss to the adjoining national park (Figs 1 and 2).

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Fig 3. Earthworks 2008

 

Integrating with natural regeneration on site

Fig 4. Integrating with existing vegetation on site

Works undertaken. The site was split into three management zones, with zones one and two progressively rehabilitated between 2008 and 2010, and zone 3 retained as an ongoing rock resource and storage area with some buffer planting. The rehabilitation techniques employed at each zone included:

  1. Earthworks to reduce steep embankments, provide track and bench access across the site for revegetation works and provide for future potential water flow across the site with a series of shallow swales and pond depressions (Figs 3 and 4);
  2. Ground disturbance to address highly compacted nature of existing surface;
  3. Removal of waste materials where possible – this included the recycling of 260 tonnes of metal that had been buried/dumped across the site;
  4. Addition of Coarse Woody Debris, primarily in windrows to provide wind shelter and thatch to hold straw and create microclimate. This material was sourced from logs and tree crowns removed during local trail clearing;
  5. Addition of compost production and water crystals to individual planting holes
  6. Planting 110,000 tubestock of 11 species from locally collected seed and cuttings in three stages;
  7. Mulching with rice straw;
  8. Weed control prior to pre works;
  9. Spreading of woodchip in weed prone areas such as access tracks and temporary nursery location.

After high initial browsing on planted seedlings by wallabies, deer and rabbits, most planting areas were progressively fenced. The steel 1.8 metre high fence had rabbit-proof netting to 1.05m high with a 300mm skirt pinned/rocked to ground, and hinge joint wire to 1.8m (Photo 4). Once in place, almost 100 percent plant establishment success was achieved.

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Fig 5. Flowering Acacia influencing nutrient status

Results to date. Soils and soil function. Monitoring has shown that three years after revegetation, soil infiltration, nutrient cycling and leaf litter values are still lower than the reference site, but soil stability measures are currently higher, possibly due to the role of young plants in binding the soil. Litter levels have understandably decreased since the original application of mulch and the amount of exposed rock has increased. It is expected that the growth of the revegetation will produce increasing amounts of litter and reverse this trend.

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Fig 6. Development of planted vegetation 6 years on

Vegetation. BioMetric http://www.environment.nsw.gov.au/papers/BioMetricOpManualV3-1.pdf was used to assess the condition of the vegetation along a 30m transect at 4 years after planting. This showed that the plantings had not yet developed to overstorey height but many of the Ribbon Gum had grown to midstorey height, providing a cover of 7.5%. The ground cover was mostly litter (52%) and rock (52%) with 2% bare ground. Native shrub cover of the ground layer was 20%, grasses 2% and forbs 8%. No exotic species were encountered along the transect so the total of 30% plant cover in the ground layer was all native. The number of woody stems was high (990) and similar to the control site. The level of exotic species incursion to the site was very low.

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Fig 7. High levels of coarse woody debris on site

Fauna. Rehabilitation works have greatly improved the habitat values of Snowy Adit, as evidence by increasing fauna recorded at the site. Pre- and post-treatment surveys have shown that, 5 years after revegetation commenced, the site is now used by at least sixty vertebrate species – 36 birds, 17 mammals, four reptiles and three frogs. Thirty-nine species were not recorded in the original 2006 survey, with 19 species (15 birds, two mammals and two frogs) attributed as a direct result of the rehabilitation works undertaken since 2006. Five threatened species were recorded in the rehabilitation area, with one additional listed species, the Powerful Owl (Ninox strenua), located in immediately adjacent forest. These threatened species were the Eastern Pygmy-possum (Cercartetus nanus), Eastern Bent-winged Bat (Miniopterus orianae oceanensis), Eastern False Pipistrelle (Falsistrellus tasmaniensi ), Gang-gang Cockatoo (Callocephalon fimbriatum ) and Flame Robin (Petroica phoenicea). The first three threatened species were not located in the original 2006 survey. The most outstanding discovery was the location of four Eastern Pygmy-possums within the fenced area of the rehabilitation area. Sixteen bird species now appeared to be either resident or regular visitors within the plantings rather than occasionally ranging into the area from adjacent forest; with nests of five species located. Several species were observed feeding flying dependent young juveniles within the planting area – such as the White-browed Scrubwren (Sericornis frontalis) and Rufous Whistler (Pachycephala rufiventris).

It is considered likely that, over time, some 29 species (23 birds, four reptiles and two mammal species) which were only recorded in adjacent forest and control sites in the current or original surveys will recolonise the area as the plantings continue to grow.

Lessons learned and future directions. The attention to detail in site preparation to create soil surface roughness and niches and microclimates in denuded and exposed sites at Snowy Adit is likely to explain the level of success achieved to date in terms of vegetation and habitat development. Constantly revisiting the site has also played an important role as it allowed measures to be taken to address overgrazing by both native and pest species. Taking the time to plan the works but also having flexibility to adapt and seek opportunities reaped benefits. A fortuitous supply of unwanted coarse woody debris and woodchip stockpiled at a nearby work depot also assisted with the establishment and growth of plants, controlled weeds and accelerated the return of native fauna using the for site as habitat.

Stakeholders and Funding bodies. The Rehabilitation of Former Snowy Scheme Sites Program was established from Snowy Hydro Limited funding and is managed by the Landforms and Rehabilitation Team in National Parks and Wildlife Service, NSW. Nicki Taws (Greening Australia Capital Region, Project Manager) conducted the vegetation monitoring. Martin Schulz conducted the fauna surveying and reporting.

Contact. Gabriel Wilks, Environmental Officer, National Parks & Wildlife Service NSW, PO Box 471 Tumut 2729, phone 062 69477070, Gabriel.wilks@environment.nsw.gov.au; Elizabeth MacPhee, Rehabilitation Officer, National Parks & Wildlife Service NSW, PO Box 471 Tumut 2729, Tel: +61 2 69477076, Email: Elizabeth.macphee@environment.nsw.gov.au.

Also read full EMR feature:Rehabilitation of former Snowy Scheme sites in Kosciusko National Park

Watch video short presentation by Liz MacPhee

Watch video short description of planting techniques Liz MacPhee

Watch video rediscovery of Smoky Mouse on rehab site Gabriel Wilks

EMR summary Restoration of Bourke’s Spoil Dump #2: https://site.emrprojectsummaries.org/2013/08/22/bourkes-gorge-spoil-dump-2-restoration-kosciuszko-national-park-2/

EMR summary Jindabyne Valve House Restoration: https://site.emrprojectsummaries.org/2013/08/20/jindabyne-valve-house-kosciuszko-national-park-nsw-2/

EMR summary Yarrangobilly Seed and Straw Production Area: https://site.emrprojectsummaries.org/2013/08/17/yarrangobilly-native-seed-and-straw-farm/

 

 

Bourkes Gorge Spoil Dump #2 Restoration – Kosciuszko National Park

 Elizabeth MacPhee and Gabriel Wilks

Bourkes Gorge Spoil Dump #2 is one of two large spoil dumps created during construction of the Murray 1 Pressure Tunnel between 1962 and 1966 to carry water from the Geehi Reservoir to the Murray 1 Pipelines.  These pipelines deliver water to the Murray 1 Power Station on the western side of Kosciuszko National Park near the township of Khancoban.  At this site during Scheme construction, approximately 300 000 m3 of unconsolidated rock spoil was removed from the tunnel access point on a rail siding and dumped in the steep valley of a tributary creek flowing to Bogong Creek.

 The site prior to rehabilitation. Bourkes Gorge Spoil Dump #2 was one long unstable rock slope devoid of native vegetation with scrap metal, timber and concrete jutting out along erosion scars. It was too steep to stand on, with a slope height of 60m and an angle of approximately 380. The spoil dump was 150m wide across the valley and extended about 250m upstream, blocking the tributary creek. As a result, an 8m washout scar was left in the southern side of the spoil dump with continual erosion down the creek, eroding particularly during peak flows.

Fauna and vegetation surveys were conducted on and in the surrounding forest. Three fauna species listed as vulnerable under the NSW Threatened Species Conservation Act 1995 (TSC Act) were identified in the surrounding forest – the Yellow-bellied Glider Petaurus australis, Gang-gang Cockatoo Callocephalon fimbriatum and the Eastern False Pipistrelle Falsistrellus tasmaniensis. (Schultz, M unpublished). Habitat requirements for nesting and roosting of these species did not occur within the site.  The Spotted Tree Frog Litoria spenceri is listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) and is also listed in the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the TSC Act. This species was known to occur in the vicinity of site, but surveys had recorded a dramatically declining population (Hunter & Gillespie 1999). It was not recorded on or around the site during the fauna survey in 2008. Weeds such as Blackberry (Rubus sp.) and willow (Salix spp.) occurred at the top edge of the site and minimal vegetation was found on the majority of the spoil.

Objectives of the restoration works :

  • Re-shaping the spoil dump to a more stable slope.
  • Constructing an environment that favoured revegetation and habitation of site-indigenous flora and fauna species.
  • Integrating the site into the surrounding tall montane forest
  • Constructing a channel to enable high water flow events to move across the site without scouring or rendering the site unsafe.
  • Slowing high flow events to limit the scour effects on the downstream environment.
  • Safely managing contamination or general construction waste found at the site

Treatments. Works were undertaken from December 2009 to April 2010. Stabilisation works consisted of reshaping the spoil dump and lining 300m of artificial creek line. The resulting land form was planted with 50,000 tubestock in 2010 – 2011 and had specific management practices applied to minimise potential impact on the Spotted Tree Frog.

Plant species used in the revegetation had to be sourced from plants as cuttings, seed or division from the surrounding environment, capable of being commercially propagated due to the number required, and robust enough to withstand the more extreme conditions found on site than in surrounding forest. One rare species Bertya findalyii was found colonising the edge of the site and so was incorporated into the planting list.

Results.

Erosion Control.  The rehabilitation of the Bourkes Gorge #2 spoil dump resulted in 43,300 m3 of rock soil being re-shaped to reduce slope and direct water flow, reducing the potential for surficial erosion and mass slumping. Slope angles were reduced from around 38ْ to between 26ْ and 30ْ  (URS, 2009). Around 560M3 of concrete reinforced with structural synthetic fibre and on site rock was used to form the water channel. In the three years since rehabilitation, there have been two major flood events in the region – October 2010 and March 2012. The Jagungal weather station in Kosciuszko NP recorded 6, 12 and 24 hour duration rainfall intensities exceeding the 100 year Average Recurrence Interval (ARI) intensity. There was no evidence of erosion or slumping at Bourkes Gorge Site following these events.

Revegetation.  Assessment of the vegetation was done two years after planting by Greening Australia Capital Region using BioMetric (http://www.environment.nsw.gov.au/papers/BioMetricOpManualV3-1.pdf).  This monitoring has shown outstanding survival and growth rates – with 35% cover by 19 native species, with virtually nil weed. (Species are listed in Table 1 ).

Lesson learned: Rock spoil in high altitude, steep conditions with no organic matter in a compacted and unstable condition will not naturally revegetate, even if left for a fifty year period.  Applying site appropriate techniques such as re-shaping for stability, allowing for water flow, moving compacted rock to create air pockets and allow water infiltration, and adding the essential ingredients of organic matter, nutrients and plant material can trigger successful site revegetation. Covering the ground with a layer of organic matter such as rice straw ameliorates temperature extremes on site, allowing young seedlings to survive and flourish.

Acknowledgements. Thanks are extended to the restoration team at Kosciuszko National Park, including the many contractors who participated.  We also thank Nicki Taws and Angela Calliess (Greening Australia Capital Region) who undertook the formal vegetation monitoring.

 

After earthworks, planting niches are filled with compost

After earthworks, planting niches are filled with compost

Main slope at Bourkes Gorge #2 spoil dump

Main slope at Bourkes Gorge #2 spoil dump

Liz MacPhee pictured at Bourkes spoil dump one year after planting

Liz MacPhee pictured at Bourkes spoil dump one year after planting

Table 1. Vegetation data recorded on a 50m transect approximately 2 years after treatment.  (Data from Greening Australia Vegetation Monitoring Former Snowy-Hydro Sites Kosciuszko National Park).

Scientific name

Common name

Tube stock

Direct seeding

Transplants from within site

Trees  

 

 

 

Eucalyptus dalrympleana Mountain Gum

X

   
Eucalyptus delegatensis Alpine Ash

X

X

 
Eucalyptus globulus v bicostata Southern Blue Gum

X

   
Eucalyptus viminalis Manna Gum

X

   
Lomatia fraseri Tree Lomatia

X

   
Shrubs  

 

 

 

Acacia dealbata Silver Wattle

x

   
Acacia melanoxylon Blackwood wattle

X

   
Bedfordia arborescens Blanket leaf

X

   
Bossiaea foliosa Leafy Bossiaea

X

   
Bertya findlayii Alpine Bertya

X

   
Cassinia longifolia Shiny Cassinia

X

   
Coprosma hirtella Rough Coprosma

X

   
Coprosma quadrifida Prickly Currant Bush

X

   
Daviesia mimosoides subsp. laxiflora Mountain bitter pea  

X

 
Helichrysum stirlingii Ovens Everlasting

X

   
Kunzea ericoides Burgan

X

   
Leptospermum grandiflorum Mountain Tea Tree

X

   
Leptospermum obovatum River Tea Tree

X

   
Polyscias sumbucifolia Elderberry Panax

X

   
Pomaderris aspera Hazel Pomaderris

X

   
Prostanthera lasianthos Mint bush

X

   
Forbs  

 

 

 

Derwentia derwentiana Derwents Speedwell

X

   
Dianella tasmanica Mauve Flax lily      
Senecio linearifolius Tall Senecio

X

   
Stellaria pungens Prickly starwort

X

   
Ferns        
Polystichas proliferatum Mother Shield-fern

X (divisions)

   
Blechnum spp. fern    

X

Grasses  

 

 

 

Poa ensiformis  

X

X

 
Poa  helmsii Broad leafed snow grass

X

X

 
Poa sieberiana Tussock grass

X

X

Yarrangobilly Native Seed and Straw Farm

Elizabeth MacPhee and Gabriel Wilks

Yarrangobilly Caves is a tourist destination within Kosciusko National Park (KNP), New South Wales. The Yarrangobilly Caves Wastewater Treatment Plant (WTP) has been established to treat greywater produced at the tourist centre, to stop nitrogen moving into the limestone karst system of the caves.

To optimise benefits from the WTP, the Rehabilitation team undertook the planting of locally native grass species in the discharge area, with a view to producing seed and weed-free mulch for use in the KNP Former Snowy Sites restoration program.

Effluent is initially treated using a bacterial blivet and then undergoes an ultra-violet treatment process so that it is within a “greywater” classification. It is then stored in a 200,000 litre tank and released under pressure to a discharge area. Prior to being discharged the effluent is diluted with fresh water to an average ratio of 7:3 (effluent:fresh water) in order to reduce the total nitrogen in the irrigated water to around 10 mg/L, which has been used as a threshold figure for nutrient loading. Once at the right concentration, the effluent is discharged in a large flat sedimentary rock area of about 1 ha in size.  The irrigation area in which the plant species are grown is approximately 0.5 ha.

Vegetation treatments. From 2006 to 2010, some 20,000 plants of a number of species of the grass genus Poa were planted in the discharge area of the WTP, at 50cm spacings (Fig 1).  The four main species were: Poa costiniana; P. fawcettiae, P. sieberiana and P. ensiformis; all native to KNP. Over the last 6 years, more than 300 kilos of highly viable Poa spp. seed has been collected and used in restoration works across the Park. The thatch (seed heads and cut off straw) has also been harvested and used as mulch on some of the sites.

Other species needed for rehabilitation in KNP have also been planted in the site over the last two years. Bossiaea foliosa and Lomandra longifolia have been grown for seed production and a variety of difficult to germinate shrubs have been grown to provide cutting material for propagation.

Soil sampling and soil treatments. Sampling was conducted prior to and after plant harvest to gauge the soil’s physical and nutrient status.  The samples (10cm cores of topsoil and subsoil) were sent to the Environmental and Analytical Laboratories at Charles Sturt University for analysis of Total Phosphorus and Total Nitrogen. (ammonia and nitrates as Nitrogen and phosphorus as Phosphorus (Bray)).

As early soil tests showed that pH reduced, Lime was applied to the discharge area in 2010 at 1 – 1.5 tonnes to to raise topsoil pH approximately 1 unit.

Results.

Seed and mulch production: Within the first 18 month period, nearly 100 kilos of seed was collected. To date over 300 kilos of highly viable Poa spp. seed has been collected and used in rehabilitation across the park, with the 2011/2012 harvest producing approximately 58 kilograms of seed. In the 2012-12 harvest, an estimated 288 kilograms of thatch was removed for use as mulch in restoration areas in the Park.

Soil fertility. More nitrogen and phosphorus was discharged during the 2011/2012 season than could be removed by plants season, with the native species having naturally low nutrient removal rates. Annual soil monitoring and peizometer monitoring of the ground water is keeping track of the use and movement of nitrogen in this landscape and to monitor any changes in soil chemistry.

 Suggestions for improvements:

  • Review irrigation scheduling to ensure the bulk of irrigation is occurring from November to March when nutrient uptake will be at its highest (rather than in the cooler months).
  • De-thatch the grass species at the start of spring to encourage fresh re-growth and therefore improve nutrient uptake over the spring and summer months
  • Test effluent on a regular basis to assess salt load;
  • Further treat effluent to reduce the nitrogen, phosphorous and sodium load;
  • Monitor and adjust pH as required; and
  • Reseed bare patches to maximise nutrient uptake by plants.

 In 2012 a progressive replacement planting program commenced, where sections of the oldest plants were poisoned and replaced with young plants. This continual renewal replanting will ensure the plantation remains actively growing, taking up maximum levels of nutrient and producing high quality seed and mulch.

Acknowledgements.  Funding for this project came from The Former Snowy Sites Rehabilitation project with soil and plant nutrient data provided by D.M McMahon (2008, 2012): Environmental Monitoring Use of Effluent for Irrigation, Yarrangobilly Caves, NSW. Environmental Consultants (agronomy) Wagga, Wagga.

Yarrangobilly grasses ready for harvesting

Yarrangobilly grasses ready for harvesting

The plantings are mainly four local species of Poa

The plantings are mainly four local species of Poa